As outlined in this paper, the patient with disseminated malignancy suffers many alterations of hemostasis; in addition, hemorrhage or less commonly thrombosis is the final clinical event in many of these patients. Patients with malignancy present a major clinical challenge in this day of new oncological awareness and more aggressive care. Thus, it is important to realize that these alterations of hemostasis do exist and they must be approached in a logical manner with respect to diagnosis as well as efficacious therapy. By far the most common alteration of hemostasis in malignancy is that of hemorrhage associated with thrombocytopenia either drug-induced or from bone marrow invasion. However, hemorrhage due to disseminated intravascular coagulation is also quite common. In addition, many antineoplastic drugs, as well as radiotherapy, may lead to hemorrhage in these patients. Thrombosis, which is also commonly seen in the patient with malignancy, is usually a manifestation of disseminated intravascular coagulation manifest as an intravascular thrombotic rather than an intravascular proteolytic event. When suspecting this, confirmatory laboratory evidence must be sought and the patient treated apropriately. When approaching the patient with malignancy and either hemorrhage or thrombosis, all of the potential defects in hemostasis must be taken into account, defined from the laboratory standpoint, and treated in as precise a manner as possible.